Cellulose acylate films are widely used in optical applications such as protection films for polarizing plates since they can be easily produced in the form of films that have excellent transparency and low refractive index an isotropy.
Accompanying increases in the range of applications of liquid crystal display devices and the places they are used, there is an increasing demand for the protection film surface to have high mechanical strength in order to prevent damage to the display screen.
However, cellulose acylate films have the drawbacks of a small modulus of elasticity and a low surface hardness in comparison with polyester films, which are often used as protection films, etc.